The present invention relates to power supplying apparatus and method for a vehicle drive device that drives an engine or a motor of a hybrid automobile and particularly control operation of precharge contactor for supplying an electric power from a high voltage battery to a capacitor of a power drive unit.
Conventionally, a vehicle drive device that drives an engine, a motor of a hybrid automobile and the like, are provided with a high-voltage battery that generates a high voltage and a sub-battery that generates a low voltage for supplying an electric power to auxiliaries such as a starter and the like. The electric power from the high voltage battery is supplied to a motor in way of a contactor serving as an electromagnetic switch and a power drive unit.
The power drive unit includes a switching element such as a transistor or the like, in which a high-capacitance capacitor is connected in parallel with the switching element in order to prevent a voltage from the power supply from being altered, while the switching element is turned on or turned off. Here, electric power from the high voltage battery used for the power drive unit is supplied by opening or closing of the contactor. However, if the contact were immediately on, larger current might be flown into the contactor in order to charge the capacitor and a value of the larger current would be over an allowable current value of the contactor.
Thus, conventionally a precharge contactor is disposed, which is connected in parallel with the main contactor and connected in series with a current-restriction resistor, apart from the main contactor that is directly couples to a power supplying path. When charging the capacitor, firstly the precharge contactor is turned on and secondly after charging of the capacitor is completed, the main contactor is turned on. By such a control procedure using the electric power supplying apparatus, the conventional technology prevents the larger current from being flown into the main contactor. In other words, when charging the capacitor, a signal for closing i.e. turning on the precharge contactor is outputted from the power supplying apparatus, and an electric power is supplied to a drive coil of the precharge contactor, resulting in that the precharge contactor is turned on.
Now, when energizing the engine, a voltage drop of the sub-battery occurs owing to electric consumption by the starter and the like. Even if the power supplying apparatus output an on-command to the precharge contactor, the drive coil might not be sufficiently excited, resulting in that the precharge contactor might not be sometimes on. Therefore, a precharge contactor to be normally activated might not be normally activated, sometimes.
Further, if the temperature of the drive coil of the contactor were extraordinarily risen, current of the coil might not be decreased, so that a magnetic force might not generate only for activating a contact mechanism of the contactor, resulting in that the contact mechanism of the contactor might be not activated. As a conventional countermeasure, Japanese Patent Laid-open No. 10-22490 discloses regarding in that those operational matters might be beforehand informed of e.g. an automobile driver by measuring the temperature of the drive coil of the contactor using a sensor.
According to the disclosure, it has not been relatively easy to directly measure the temperature of the coil of the contactor, because the contactor has been sealed using a casing for water-proof and/or dust proof. Additionally, a whole system might sometimes be likely to be complicated in order to monitor the coil temperature of the contactor sealed using the casing.
It is an object of the present invention to provide a power supplying apparatus in that the power supplying apparatus used for the vehicle drive device can prevent failure of the precharge contactor from occurring owing to a voltage-drop of the sub-battery while the engine is being energized without intention based on misjudgment. It is another object of the present invention to provide the power supplying apparatus in that the power supplying apparatus used for the vehicle drive device can prevent operational failures of the contactor owing to rising of temperature.
According to an aspect of the present invention, there is provided a power supplying apparatus used for a vehicle drive having: a motor that assists an engine that outputs a driving force to the vehicle and/or drives the vehicle; a first charging device that supplies an electric power to the motor; a main contactor connected between the first charging device and the motor; a precharge circuit including a precharge contactor connected in parallel with the main contactor and a current-restriction resistor; a power drive unit including a switching circuit disposed at an input side of the motor in which plural switching elements are connected; a capacitor connected in parallel at an input side of the power drive unit; a second charging device that supplies a drive voltage that is smaller than a voltage of the first charging device at least to a drive coil of the precharge contactor; an intial charging unit for supplying the drive voltage to the drive coil so that a voltage of the capacitor becomes a predetermined value or larger by closing the precharge contactor; and an initial charging retrying unit that retries to execute an initial charging after the initial charging is once stopped and predetermined time elapses if a voltage across the capacitor is less than a predetermined value and if a voltage at the second charging device is a predetermined value or smaller.
In view of the aspect, following effects can be attained. The initial discharging unit supplies the drive voltage at the second charging device to the drive coil, resulting in that the precharge contactor is inactivated and charging operation is executed at a predetermined interval so that the voltage across the capacitor becomes a predetermined value or larger. After charging time by the initial charging unit has elapsed at a predetermined interval, in a case where the voltage across the capacitor is smaller than a predetermined value and the voltage at the second charging device is smaller than a predetermined value and the voltage from the second charging device is a predetermined value or smaller, the initial charging is retried to be executed at a predetermined interval. Accordingly, e.g. if a predetermined value of a voltage at the second charging device is set as a moving voltage which can inactivate the precharge contactor, a voltage drop in the second discharging device occurs while the engine is being energized and the voltage becomes the moving voltage or smaller, resulting in that the precharge contactor is not normally on. Even in such a case, after the voltage is recovered into an original voltage value by the execution of the retry.